The Armstrong Whitworth F.K.5 and F.K.6 were experimental triplanes built as escort fighters by Armstrong Whitworth during the First World War. They carried two gunners in nacelles mounted on the centre wing. One example of each type was built, with no further development or production following.
In early 1916, the British War Office drew up a specification for a multi-seat escort fighter to be powered by one of the new Rolls-Royce Eagle engines, with an endurance of at least seven hours, intended to protect formations of bombers from German fighters such as the Fokker E.I, with an additional role of destroying enemy airships. Orders were placed for prototypes from Armstrong Whitworth, Sopwith and Vickers, all of which were of unconventional design owing to the need to give their gunners a good field of fire in the absence of an effective synchronisation gear to allow guns to be fired safely though the propeller disc.[1]
F.K.5edit
Armstrong Whitworth's chief designer, Frederick Koolhoven's first design to meet this requirement, probably designated F.K.5,[8] was a large, single-engined tractortriplane with the middle wing having a much greater span than the upper and lower wings. The gunners were housed in two long nacelles mounted on top of the middle wing, allowing them to be seated ahead of the propeller disc, with the pilot's cockpit situated behind the wings in the slim central fuselage, giving a poor view. The undercarriage consisted of a sprung strut carrying two mainwheels underneath the engine, with two stabilising wheels at the wingtips of the lower wing, with a tailskid just aft of the trailing edge of the lower wing.[9][10] This design never flew, with the head of Armstrong Whitworth's Aircraft department, I. Fairbairn-Crawford, forbidding test flights.[11]
F.K.6edit
Koolhoven completely reworked the design to produce the F.K.6. While still a triplane with the middle wing of significantly greater span than the upper and lower wings, it was larger, with two-bay wings. This time, the gunner's nacelles were slung under the middle wing and were shorter, so that the gunners sat behind and outboard the propeller (and less than 2 ft (0.6 m) from the exhaust manifold).[7] The fuselage was much deeper than the F.K.5, filling the gap between the middle and lower wings, giving a slightly better view, while the undercarriage had two pairs of wheels with a narrow track under the fuselage and a more conventional tailskid.[12]
Four examples of the F.K.6 were ordered in April 1916,[12] two of which were intended for the Royal Naval Air Service,[5] but only one was built, this demonstrating poor performance when tested. As effective synchronising gears were now available, the type was abandoned, with none of the escort fighters being brought into production.[13][14]
Specifications (F.K.6)edit
Data from War Planes of the First World War: Volume One[15]
^Royal Air Force Museum Aircraft Thesaurus - Armstrong Whitworth 26 July 2011 at the Wayback Machine. Royal Air Force Museum, 2005. Retrieved 19 July 2009.
^No definitive list exists of the true sequence of the F.K. designations as applied by Koolhaven to his designs.[2] While the escort triplanes were probably designated F.K.5 and F.K.6, and were earlier in design than the F.K.8 and F.K.9 and 10 designs,[3][4][5] many other sources refer to the types as the F.K.12.[1][6][7]
armstrong, whitworth, armstrong, whitworth, were, experimental, triplanes, built, escort, fighters, armstrong, whitworth, during, first, world, they, carried, gunners, nacelles, mounted, centre, wing, example, each, type, built, with, further, development, pro. The Armstrong Whitworth F K 5 and F K 6 were experimental triplanes built as escort fighters by Armstrong Whitworth during the First World War They carried two gunners in nacelles mounted on the centre wing One example of each type was built with no further development or production following F K 6Role Escort fighterNational origin United KingdomManufacturer Armstrong WhitworthDesigner Frederick KoolhovenNumber built 2 Contents 1 Development and design 1 1 F K 5 1 2 F K 6 2 Specifications F K 6 3 See also 4 Notes 5 References 6 External linksDevelopment and design editIn early 1916 the British War Office drew up a specification for a multi seat escort fighter to be powered by one of the new Rolls Royce Eagle engines with an endurance of at least seven hours intended to protect formations of bombers from German fighters such as the Fokker E I with an additional role of destroying enemy airships Orders were placed for prototypes from Armstrong Whitworth Sopwith and Vickers all of which were of unconventional design owing to the need to give their gunners a good field of fire in the absence of an effective synchronisation gear to allow guns to be fired safely though the propeller disc 1 F K 5 edit Armstrong Whitworth s chief designer Frederick Koolhoven s first design to meet this requirement probably designated F K 5 8 was a large single engined tractor triplane with the middle wing having a much greater span than the upper and lower wings The gunners were housed in two long nacelles mounted on top of the middle wing allowing them to be seated ahead of the propeller disc with the pilot s cockpit situated behind the wings in the slim central fuselage giving a poor view The undercarriage consisted of a sprung strut carrying two mainwheels underneath the engine with two stabilising wheels at the wingtips of the lower wing with a tailskid just aft of the trailing edge of the lower wing 9 10 This design never flew with the head of Armstrong Whitworth s Aircraft department I Fairbairn Crawford forbidding test flights 11 F K 6 edit Koolhoven completely reworked the design to produce the F K 6 While still a triplane with the middle wing of significantly greater span than the upper and lower wings it was larger with two bay wings This time the gunner s nacelles were slung under the middle wing and were shorter so that the gunners sat behind and outboard the propeller and less than 2 ft 0 6 m from the exhaust manifold 7 The fuselage was much deeper than the F K 5 filling the gap between the middle and lower wings giving a slightly better view while the undercarriage had two pairs of wheels with a narrow track under the fuselage and a more conventional tailskid 12 Four examples of the F K 6 were ordered in April 1916 12 two of which were intended for the Royal Naval Air Service 5 but only one was built this demonstrating poor performance when tested As effective synchronising gears were now available the type was abandoned with none of the escort fighters being brought into production 13 14 Specifications F K 6 editData from War Planes of the First World War Volume One 15 General characteristicsCrew 3 Length 37 ft 0 3 4 in 11 297 m Wingspan 62 ft 0 in 18 90 m Height 17 ft 0 in 5 18 m Powerplant 1 Rolls Royce Eagle water cooled V 12 engine 250 hp 190 kW Armament Guns 2 303 in Lewis guns one in each nacelleSee also editAircraft of comparable role configuration and era Sopwith L R T Tr Vickers F B 11Notes edit a b Bruce 1957 p 25 Tapper 1988 p 8 Tapper 1988 pp 72 73 Royal Air Force Museum Aircraft Thesaurus Armstrong Whitworth Archived 26 July 2011 at the Wayback Machine Royal Air Force Museum 2005 Retrieved 19 July 2009 a b Green and Swanborough 1994 p 25 Bruce 1965 p 14 a b Mason 1992 p 81 No definitive list exists of the true sequence of the F K designations as applied by Koolhaven to his designs 2 While the escort triplanes were probably designated F K 5 and F K 6 and were earlier in design than the F K 8 and F K 9 and 10 designs 3 4 5 many other sources refer to the types as the F K 12 1 6 7 Tapper 1988 pp 70 71 Bruce 1965 pp 14 16 Bruce 1965 p 16 a b Tapper 1988 p 71 Bruce 1957 p 26 Lewis 1979 p 99 Bruce 1965 p 17 References editBruce J M British Aeroplanes 1914 18 London Putnam 1957 Bruce J M War Planes of the First World War Volume One Fighters London Macdonald 1965 Green William and Swanborough Gordon The Complete Book of Fighters New York Smithmark 1994 ISBN 0 8317 3939 8 Lewis Peter The British Fighter since 1912 London Putnam Fourth edition 1979 ISBN 0 370 10049 2 Mason Francis K The British Fighter since 1912 Annapolis Maryland USA Naval Institute Press 1992 ISBN 1 55750 082 7 Tapper Oliver Armstrong Whitworth Aircraft since 1914 London Putnam 1988 ISBN 0 85177 826 7 External links editKoolhoven Aeroplanes Foundation Retrieved from https en wikipedia org w index php title Armstrong Whitworth F K 6 amp oldid 1213232479, wikipedia, wiki, book, books, library,
